Wrench



D- 17 1940 s. MANDL 2,225,420

WRENCH .Filed June 24, 1938 A2 -ShoetTs-Sheet l ATTORNEYeS s. MANDL 2,225,120`

WRENCH Filed June 24, 1938 2 lSmets-Smm 2 BY if i ATroRNEY.

Patented Dec. 11, 1940 UNITED STATES 2,225,420 WRENCH Siegmund Mandl, Milwaukee, Wis., assignor to Blackhawk Mfg. Co., Milwaukee, Wis., a corporation of Wisconsin Application June 24, 193s, serial No. 215,622

3 Claims.

ing force has been applied to the wrench handle.

One of the principal purposes of this class of wrench is to prevent subjecting the element to which pressure is being applied, from being subjected to excessive stress, and to enable the operator to apply approximately the same safe and predetermined force to a succession ofsimilar machine elements such as threaded bolts, studs, nuts, taps, threading dies or the like. The prior wrenches of this type were generally provided with a gage and pointer, the latter of which was movable by distortion of the wrench handle to indicate upon the gage plate the pressure or forcev applied to the Work. vThese prior wrenches therefore depended upon strict observance of the gage and pointer by the operator, in order to gain the advantages obtainable by using the special wrench, and the prior wrenches were therefore practically useless for indicating purposes when utilized in dimly lighted or dark places. Since many of these wrenches are used in garages and by relatively careless operators. their utility has been limited; and it was also relatively difficult with the prior torque wrenches to obtain accurate results and to prevent overotressing of the elements to which the wrenches were applied, because of the relatively crude and ineffective indicating devices employed therein.

It is therefore an object of .the present invention to provide an improved power yindicating wrench which is highly efiicient which may be conveniently manipulated and will give accurate indications of perfomance in relatively dark and inaccessible places.

Another object of my present invention is to provide anew and useful torque wrench wherein distortion of a part of the tool during normal use, is effectively utilized to give a quick indication of the force being applied, by flashing a light when the predetermined limiting force has been reached.

vA further specific object of this invention is to provide simple, compact and readily manipulable means for effecting accurate pre-setting of t. torque wrench indicating dial, and for givin use, and

ing a signal the moment that the pre-set condition of operation has been reached.

Still another specific object of the invention is to provide a simple, compact and durable indicating wrench assemblage which need not be carefully watched by the user, and wherein the signal will startle the operator into releasing the force and will thereby avoid over-stressing of the manipulated element.

An additional object of my invention is to provide an improved torque indicating wrench which is accurate and sensitive in its indications, and which may be manufactured and sold at modcrate cost.

These and other objects and advantages of my invention will be apparent from the following detailed description.

A clear conception of the several features constituting my present improvement, and of the mode of constructing wrenches built in accordance with the invention, may be had by referring to the drawings accompanying and forming a part of this specication wherein like reference characters designate the same or similar parts in the various views.

Fig. l is an elevation of the complete torque wrench, looking directly at the indicating dial thereof;

Fig. 2 is a part sectional side-view of the and of utilizing torque' Wrench, the section having been taken longitudinally through the indicating mechanism and through a portion of the handle;

Fig., 3 is a transverse section through the wrench taken along the line 3--3 of Fig. l;

Fig. 4 is another transverse section through the wrench taken along the line 4-4 of Fig. 1;

Fig. 5 is a section through the signal light and battery compartment of the wrench, taken along the line 5-5 of Fig. l;

Fig. 6 is` an enlarged fragmentary part sectional elevation of the indicating dial, the section being taken along the irregular line 6-6 of Fig. '7; and

Fig. 7 is a similarly enlarged longitudinal central section through the indicating mechanism.

While the invention has been shown and described as being specifically embodied in a torque 'handle I3 secured to .ating portion I .any suitable manner.

ating portion I0 rigidly associated therewith and having a ratchet driving member II rotatably supported therein; a relatively flexible rod portion I2 of reduced diameter extending away from the rigid portion I0 and having an operating the free end thereof; a frame I4 firmly secured -to the end of the acturemote from the socket 9 and loosely embracing and enclosing the flexible stem portion I2; a calibrated 4gage plate I5 rotatably supported upon the frame I4 and having peripheral teeth I 6 engageable with the teeth of an adjusting pinion I1 -which is journalled in the frame I4; a pointer I8 secured to a shaft I9 which is journalled in a subframe 20, centrally of the gage plate I; a lever 2I journalled at its medial portion for oscillation upon the subframe 28 and having at one end a toothed segment 22 meshing with a pinion 23 secured to the shaft I9, and being provided at its opposite end with a slot 24 slidably engaging a pin 25 secured to the exible rod portion I2; a transparent closure 26 for the gage plate I5 and pointer I8; a flash light bulb 21 mounted in a socket 28 secured to the main frame I4 adjacent to the adjusting pinion I1; and a battery 29 mounted in a recess 38 in the main frame and being luminate the same under certain conditions of operation o1' the wrench.

The socket 9 need not necessarily be of the ratchet type, but may be of any other desired formation, and the socket and bar portions I0, I 2 may be formed either of one piece of stock or of several pieces rigidly connected to each other in The handle I3 maybe formedfor convenient gripping. and may be attached to the free end of the reduced I2 in any desired manner. The main frame I4 which isxfirmly attached to the enlarged rod portion I0, does not contact directly with the flexible rod portion I2, so that the reduced portion I2 may deflect laterally when the socket 9 Is associated with the work and a pull is applied to the handle I3. 'I'he gage plate I5 which may be calibrated or graduated in any desired manner, is rotatably conned within a bore of the main frame I4 by means of a coil spring 3I, the outer end of which coacts with the glass closure 26 and the inner end of which presses against a washer 32 which in turn engages the toothed peripheral portion of the plate I5 so 'as to protect and confine the teeth I8 while permitting free rotation of the plate I5 with the aid of the pinion I1. The transparent closure 28 is normally held in place hv means of a retainer ring 33 coacting therewith and removably attached to the frame I4. so as to provide a sealed enclosure for the dial: and the pinion I1 which `meshes with the teeth I 5 of the gage plate I5. is journalled upon a fixed stud 35 and is rotatable by direct application of a. finger or thumb to the teeth thereof. The pinion I1 may be locked in adjusted position by means of a clamping knob 34 coacting with the stud 35 and with the main.. frame I4. It should be noted, that while the teeth I5 and those of the pinion I1 are of the spur type, these teeth may be of the spiral or worm type if a selflocking arrangement is desired.

The gage disk or plate I5 is preferably formed of insulating material, and is provided with an upwardly projecting contact post 35 located at ythe zero graduation and adapted to be engaged by the tip Aof the pointer I8; and also has secured to the inner face thereof a flat conductor comestible with the bulb 21 to' u rod portion ring 31 to which the post 3S is attached. The supporting shaft I9 for the pointer I8 does not contact the gage plate I5 but is journalled for rotation in the subframe 20 which is firmly attached to the main frame I4 by means of screws 38,V and the rotation of the shaft I 9 may be slightly retarded by a friction spring 39 secured to the frame 20 and coacting with a hub 40 carried by the pointer shaft. The screws 38 coact with slots 4I in the frame 20 so as to permit adjustment of the subframe relative to the main frame I4 for the purpose of properly positioning the pivot pin 42 of the lever 2|, and one of the screws 38 serves to clamp a stationary resilient contact 43 in position so that this contact will constantly engage the conductor ring 31. The fixed Contact 43 Iis insulated from the screw 38 and frames I4, 30 by means of bushings 44, and is connected to the lamp socket 28 by an insulated lead 45, see Figs. 5 and 6. The flash light battery 29 is connned within the frame recess 30 by a removable plug 48, and has its outer casing in direct electrical contact with the frame I4, while the battery terminal 41 engages a resilient contact plate 48 with which the lower end of the bulb 21 concts as clearly shown in Fig. 5. The arrangement is obviously such, that when the pointer I8 engages the contact post 38, the bulb 21 will be illuminated, and the disk or plate I5 should crdinariiy be so positioned that such completion of the electric circuit will not be maintained for any great length of time.

During normal use of my improved torque wrench, and assuming that it is desirable to apply a succession 'of nuts to studs with a predetermined degree of torque or pressure, the gage plate I5 should firstbe adjusted either to the right or left of the normally fixed point of the pointer I8, by releasing the knob 34 and manipulation of the pinion I1. If the Wrench is to cooperate with elements which require movement of the handle I3 in a clockwise direction as viewed in Fig. 1, then the gage plate I5 should be shifted in a counterclockwise direction about the axis of the shaft I9, and vice versa. When the desired graduation of the dial has been brought into registry with the pointer I8 and `the pinion I 1 has been locked with the aid of the knob 34,-the wrench may be applied to the work and a pull may be exerted upon the handle I3. As the resistance set up by the Work becomes sufficient to cause the flexible rod portion I2 to bend, the pin 25 coacting with the slot 24 in the lever 2|, will swing this lever about its pivot pin 42 thereby causing the toothed segment 22 to rotate the shaft I 9 and pointer I8 through the lpinion 23. When this bending distortion becomes wrench and causes him to -release the pressure immediately when the light is flashed.

Prom the foregoing description it will be apparent that the improved torque wrench may be utilized to accurately predetermine the force which should be applied to perform a certain piece of work, and that the same results may be duplicated as often as desired. The flashing of shock coil or a bell signal, without the exercise of invention. The initial or normal position of the pointer I8 may be accurately fixed by adjustment of theI subframe 20 with the aid of the screws 38 and slots 4l, and the dial is readily accessible upon removal of the retainer ring 33. The dry-cell or battery 29 may be conveniently replaced upon removal of the plug 46, and the light bulb 21 may also be readily removed. It should be noted that the xed resilient contact 43 coacting with thecontact ring 31 insures con- -tinuity of the electric circuit to the post 36 regardless of the lposition of adjustment of the gage plate l5, and the bulb 21 will be illuminated immediately upon engagement of the pointer I8 with the post 36. The improved wrench has proven highly satisfactory in actual use, and presents a neat appearance and can obviously be manufactured at moderate cost.

It should be understood that it is not desired to linut this invention tothe exact details of construction or to the precise mode o use, herein shown and described for various modifications within the scope of the appended claims may occur to persons skilled in the art.

I claim:

l. A portable torque wrench comprising, a

work engaging member, a handle member for actuating said work engaging member, a deflectable connection between said members, a frame carried by one of said members and extending along said connection toward the other member, a graduated circular dial adjustable upon said frame and having thereon a normally fixed electrical contact definitely located with respect to the dial graduations, means coacting I5 has been properly set, and also makeswith the/periphery of said dial for effecting adjustment thereof and of said contact about the central dial axis, a pointer swingable about said axis upon deiiection of said connection and constituting the movable contact for completing an electric circuit, and an electric signal carried by said frame near said dial and being operable upon completion of said circuit by said pointer.

2. A portable torque Wrench comprising, a work engaging member, a handle member for actuating said Work engaging member, a deiiectable connection between said members, a frame carried by one of said members and extending along said connection toward the otherl member, a graduated peripherally toothedj'circular dial adjustable upon said frame and having thereon a normally fixed electrical contact ldefinitely located With respect to the dial graduations, a -pinion coacting with thel peripheral teeth of said dial to effect adjustment thereof and of said contact about the central dial axis, a

pointer swingable about said axis upon deiiection of` said connection and constituting the mov'able contact for completing an electric circuit, and an electric light carried by said frame near said dial and being illuminable upon completion of said circuit by said pointer.

3. A portable torque wrench comprising, a work engaging member, a deectable connection secured to said member and having a handle remote from said member, a frame carried by said member and extending along said connection toward said handle, a peripherally toothed graduated circular dial adjustable upon said frame and having thereon a normally xed electrical contact disposed near the zero graduation of said dial, a pinion coacting with the peripheral teeth of said dial to effect adjustment of the dial and contact about the central dial axis, a pointer swingable about said axis upon deection of said connection and constituting the movable contact for completing an electric circuit, an electric light carried by said frame near said dial and being illuminable upon completion of said circuit by said pointer, and a battery for illuminating said light housed within said frame.

SIEGMUND MANDL. 

